Multifunctional paints and caulks with controllable electromagnetic properties

ABSTRACT

An electrically conductive paint/caulk is disclosed that may be applied by spraying, rolling, and/or brushing using conventional techniques/may be dispensed from a tube. The electrically conductive paint/caulk has a plurality of metal-coated fibers precision chopped to short lengths, optionally a plurality of conductive filament structures having a high-aspect ratio, and a polymer base. The metal-coated fibers and optional conductive filament structures are dispersed uniformly within the polymer base to create a complex electron transport system facilitating conductivity sufficient for a full range of electromagnetic properties including electrostatic dissipation, electrostatic discharge, and shielding. The complex electron transport system created facilitates the full range of electromagnetic properties with lower loadings of conductors, reduces viscosity, and the additional unloaded portion of paint/caulk receives other multifunctional additives.

RELATED APPLICATION

This patent application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/768,740 that was filed on Nov. 16, 2018, for aninvention titled MULTIFUNCTIONAL PAINTS AND CAULKS WITH CONTROLLABLEELECTROMAGNETIC PROPERTIES, which is hereby incorporated herein by thisreference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to paints and caulks having desiredelectromagnetic properties. More specifically, the present inventionrelates to new materials used for controlling the composition of paintsand caulks to exhibit a range of electromagnetic capabilities, rangingfrom electrostatic dissipation, through electrostatic discharge, bleed,shielding, and lightning strike (10⁸ to 10⁻³ ohm-cms), and themethodology for controlling what properties are manifested in the paintsand/or caulks while permitting other functional additives to beinserted.

Various exemplary embodiments of the present invention are describedbelow. Use of the term “exemplary” means illustrative or by way ofexample only, and any reference herein to “the invention” is notintended to restrict or limit the invention to exact features or stepsof any one or more of the exemplary embodiments disclosed in the presentspecification. References to “exemplary embodiment,” “one embodiment,”“an embodiment,” “some embodiments,” “various embodiments,” and thelike, may indicate that the embodiment(s) of the invention so describedmay include a particular structure, feature, property, orcharacteristic, but not every embodiment necessarily includes theparticular structure, feature, property, or characteristic. Further,repeated use of the phrase “in one embodiment,” or “in an exemplaryembodiment,” does not necessarily refer to the same embodiment, althoughthey may.

2. The Relevant Technology

Paint and caulking technology, particularly conductive paints and caulkshave been used for many years. Usually, such paints and caulks areheavily loaded with silver or carbon to introduce conductivity. Becausethe known conductive paints and caulks are so heavily loaded to achieveconductivity, viscosity is high and loading other additives is precludedor severely limited. The cost-effective, efficient production ofmultifunctional paints and caulks, using a broad range of paint or caulkbases, and controlling the conductive additives composition to providecertain improved electromagnetic properties, such as electrostaticdissipation, electrostatic discharge, and shielding, would represent asignificant advance beyond the conductive paints and caulks that haveheretofore been developed.

Certain paints and caulks with historically sufficient levels ofelectromagnetic shielding capabilities have been developed; for example,U.S. Pat. No. 5,366,664 issued to Varadan et al. in 1994 is directed tosuch paints and caulks. Again, the known paints and caulks havingelectrostatic discharge or shielding capability that use the presentstate of the art, are expensive, complex to make, thick, and unable toreceive other functional additive loading.

Although there have been some minor advances in paint and caulkconductivity in recent decades, the state of art remains inadequate tomeet the current and future needs of a multifunctional marketplace.

Accordingly, a need exists for more efficient, cost-effective,efficacious paints and caulks with a full range of electromagneticproperties, flowable viscosity, and have multifunctional capabilitieswhile providing desired electromagnetic properties. Achieving thedesired electromagnetic properties, such as electrostatic dissipation,electrostatic discharge, and shielding with lower loadings of conductorsreduces viscosity and the additional unloaded portion of paint or caulkmay now receive other multifunctional materials. Such paints and caulksare disclosed herein.

SUMMARY OF THE INVENTION

The present disclosure describes developments responsive to the presentstate of the art and responsive to the problems and needs in the artthat have not yet been fully solved by currently available paints andcaulks. The multifunctional paints and caulks of the present disclosureare easily implemented and provide significant advances in efficiency,cost-effectiveness and efficacy. These multifunctional paints and caulksmay be used in a broad range of situations requiring certain desiredelectromagnetic properties.

Exemplary embodiments of the paints and caulks of the present disclosuremay comprise two or three basic components; namely, 1) Precision-choppedfiber (PCF); 2) optionally, a conductive filamentary structure having ahigh aspect ratio; 3) a paint or caulk base polymer; and 4) optionallyhaving a viscosity adjusting solvent. By varying the amount and types ofthese three principal components, desired electromagnetic properties maybe achieved in low cost, low loading, and low viscosity, efficaciouspaints and caulks produced efficiently.

For purposes of this disclosure, PCF is a metal-coated fiber (such as anickel-coated fiber) chopped to a short, specific length requirement sothat when added to a paint or caulk polymer, the paint may be applied byspraying, rolling, and/or brushing using conventional techniques and thecaulk, being pliable, may be dispensed from a tube. The PCF may compriseany type of fibrous substrate, such as, for example, carbon fiber,cellulose fiber, cotton fiber, natural fibers, Kevlar, rayon, syntheticfibers, and nanofibers may be coated with a known conductive metal,including but not limited to nickel, aluminum, copper, silver, and gold.An example range of thickness for a nickel coating may be 5 to 500nanometers. Exemplary PCF is precision chopped to lengths of 0.05millimeters to 3 millimeters. For purposes of this disclosure, the term“precision chopped” means that the statistical distribution of length iswithin 50% of the mean; however, it may be preferred to use astatistical distribution of length within 10% of the mean for someembodiments. As one example, carbon fiber may be used. Because carbonhas conductivity it offers some properties not available by usingnon-conductive fibers as the substrate. An exemplary nickel-coatedcarbon fiber PCF may have a carbon fiber having a diameter of 4 to 7microns and a nickel coating of 50 to 500 nanometers, and precisionchopped to a length from 0.1 millimeters to 1 millimeter.

The PCF of this disclosure is distinguishable from random-chopped fibersand milled fibers that are known and used in the art. By their verynature, random-chopped fibers and milled fibers have an excessivelybroad distribution of fiber lengths. The use of random-chopped fibersand milled fibers have significant drawbacks, including high loading toachieve desired conductivity, high viscosity, and constrainedpercolation. By using PCF, better percolation and conductivity, andlower and more controllable viscosity and loading is achieved across thefull range of electromagnetic properties desired.

The PCF has been developed and produced by and is available fromConductive Composites Company of Heber City, Utah.

The conductive filamentary structure, such as a metal filamentarystructure, having a high aspect ratio may be nickel nanostrands (seeU.S. Pat. Nos. 7,935,415 and 7,947,773 incorporated herein by thisreference as if fully disclosed herein) or a metal filamentary powder,such as but not limited to a nickel powder, provided each has an aspectratio greater than one, and in some embodiments preferably havingbranching. Nickel nanostrands have been developed and produced by andare available from Conductive Composites Company of Heber City, Utah.Metal filamentary powders, such as nickel filamentary powder with a highaspect ratio, are known.

The paint or caulk base polymer may be water-borne or solvent-borne,one-part or two-part. The type of paint or caulk selected for a desiredpurpose will carry a load content of the PCF and optionally high-aspectratio, conductive filamentary structure fine-tuned so that it achieves adesired electromagnetic property such as electrostatic dissipation,electrostatic discharge, or shielding. The PCF and high-aspect ratio,conductive filamentary structure work together to create a comprehensivenetwork of electron transport pathways. The physical nature of PCF andthe high-aspect ratio, conductive filamentary structure(s) facilitatesthe inter-fiber electron transport within the paint or caulk volume. ThePCF act much like logs being elongated linear electron transportconduits and the conductive filamentary structures act much like tumbleweeds that electrically interconnect the logs. For some exemplaryembodiments, the use of PCF alone dispersed within a polymer base mayachieve a desired electromagnetic property for a desired purpose orapplication. By adding conductive filamentary structures into thepolymer base, the loading of PCF may be reduced commensurately, reducingcost, viscosity, and providing more space for multifunctional additives.

By using PCF and/or a nickel filamentary structure having a high aspectratio dispersed uniformly within a paint or caulk base polymer, desiredelectromagnetic properties (for example, a range including electrostaticdissipation and electrostatic discharge with volume resistivity rangingfrom 10⁸ to 10³ ohm-cm) may be achieved while maintaining lower loadsand therefore lower viscosity than known conductive paints and caulks.

Because the desired electromagnetic properties, such as electrostaticdissipation, electrostatic discharge, and shielding, can be achieved atlower loads and lower viscosity, the exemplary paints and caulks of thepresent disclosure may have robust functionality. Other particles may beloaded as functional additives giving the paints and caulk otherfunctions. By way of example only, and not to be construed as limiting,functional additives such as coloring particles, hardening agents suchas silicon carbide, lubricating agents, and magnetic particles have roomin the matrix to be added to the extent that they do not functionallyreduce the desired conductivity. Hence, colors of such paints and caulksnow may be achieved across a broader spectrum of colors and may be morevibrant. The paints and caulks may harden faster and exhibit greaterhardness. Further functionality may be exhibited by having differentfunctions in different layers of the coating. Also, other desirablefunctions now may be exhibited in the paints and caulks withoutfunctionally sacrificing the needed conductivity. However, it should beunderstood that the list of functional additives recited above is notintended to be exhaustive. Rather, those skilled in the art are awareand may become aware of other functional additives that may be added toa paint or caulk to provide another function or characteristic. Suchadditional functional additives are contemplated to fall within thescope of this disclosure.

Interrelated methods are used to achieve a desired conductivity thatwill cause the paint or caulk to manifest the desired electromagneticproperties. Those skilled in the art of electron transport throughmaterials, armed with this disclosure, intuitively and readily candetermine and fine tune the interrelationships of the components toachieve the desired electromagnetic properties to be exhibited by thepaint and caulk through known empirical means, and without undueexperimentation.

The most basic parameters fall into the combination of two or threecategories; 1) the fiber properties of the PCF; including length,diameter and coating thickness; 2) the properties of the conductivefilamentary structure having a high aspect ratio, generally beingapproximately either sub-micron or larger than a micron in basediameter; and 3) the dielectric properties of the polymer.

By matching the interplay of the fiber properties of the PCF and theproperties of the conductive filamentary structure (for example, anickel filamentary structure) with dielectric properties of the polymer,the load ratio of PCF and nickel filamentary structure to polymer toachieve electrostatic discharge may be determined and fine-tuned forthat polymer, whether it be a paint or a caulk. Generally, PCF andnickel filamentary structure may be added to increase conductivity toachieve a full range of desired electromagnetic properties (10⁸ to 10⁻³ohm-cms) and more robust functionality capabilities.

The interrelation of the PCF-metal (nickel) content, fiber diameter, andfiber length, when considered with the aspect ratio, base diameter, andthe amount of branching exhibited by the conductive (nickel) filamentarystructure, whether a filamentary powder or nanostrand, provides thedesired conductivity. When additionally considered with the dielectricand polar properties of the polymer, the combination of PCF, conductivefilamentary structure, and polymer creates a highly complex electrontransport system which is difficult to model; however, the electrontransport system may be standardly optimized by those skilled in theart, armed with this disclosure, through standard empirical derivation.

A known quantity of a certain PCF (fiber diameter, length, metal(nickel) content) may demonstrate more conductivity through increasingthe addition of the conductive (nickel) filamentary structure component.Consequently, the loading percentage PCF may be reduced significantlybecause of the increased conductive (nickel) filamentary structurecomponent. Therefore, the balance of the quantity and type of PCFagainst the quantity and type of conductive (nickel) filamentarystructure may be used to engineer the desired viscosity, electricalconductivity, and functionality.

Furthermore, given a fixed exemplary mixture of PCF and nickelfilamentary structure, the conductivity will also be determined as afunction of the polymer type. For instance, a urethane base is moreconductive than an acrylic base which, in turn, is more conductive thanan epoxy base. The respective amounts of PCF and nickel filamentarystructures may be adjusted based upon what type of polymer base is used.

These and other features of the exemplary embodiments of the presentinvention will become more fully apparent from the drawings and thefollowing description, or may be learned by the practice of theinvention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

The exemplary embodiments of the present invention is described morefully hereinafter with reference to the accompanying drawings, in whichmultiple exemplary embodiments of the invention are shown. Like numbersused herein refer to like elements throughout. This invention may,however, be embodied in many different forms and should not be construedas limited to the embodiments set forth herein; rather, theseembodiments are provided so that this disclosure will be operative,enabling, and complete. Accordingly, the particular arrangementsdisclosed are meant to be illustrative only and not limiting the scopeof the invention, which is to be given the full breadth of the appendedclaims and any and all equivalents thereof. Moreover, many embodiments,such as adaptations, variations, modifications, and equivalentarrangements, will be implicitly disclosed by the embodiments describedherein and fall within the scope of the present invention.

Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation. Unlessotherwise expressly defined herein, such terms are intended to be giventheir broad ordinary and customary meaning not inconsistent with thatapplicable in the relevant industry and without restriction to anyspecific embodiment hereinafter described. As used herein, the article“a” is intended to include one or more items. Where only one item isintended, the term “one”, “single”, or similar language is used. Whenused herein to join a list of items, the term “or” denotes at least oneof the items, but does not exclude a plurality of items of the list.Additionally, the terms “operator”, “user”, and “individual” may be usedinterchangeably herein unless otherwise made clear from the context ofthe description.

It should be understood that the drawings are schematic depictions ofvarious components and embodiments and are not drawn to scale. Schematicdepictions are being used in this application to assist in theunderstanding of relative relationships between the components.Understanding that these drawings depict only typical exemplaryembodiments of the invention and are not therefore to be considered tobe limiting of its scope, the invention will be described and explainedwith additional specificity and detail through the use of theaccompanying drawings in which:

FIG. 1 is a perspective view of an exemplary embodiment of aprecision-chopped fiber with a portion of the metal coating removed toreveal the fiber;

FIG. 2 is an end view of the exemplary precision-chopped fiber of FIG. 1showing that the coating encircles the fiber;

FIG. 3 is a representative cross-sectional view of a portion of anexemplary embodiment of a polymer base for a paint;

FIG. 4 is a representative cross-sectional view of a portion of anexemplary embodiment showing PCF dispersed throughout the exemplarypolymer base of FIG. 3;

FIG. 5 is a representative cross-sectional view of a portion of anotherexemplary embodiment showing conductive filamentary structures dispersedthroughout the exemplary polymer base of FIG. 3;

FIG. 6 is a representative cross-sectional view of a portion of stillanother exemplary embodiment showing PCF and conductive filamentarystructures dispersed throughout the exemplary polymer base of FIG. 3;

FIG. 7 is a representative cross-sectional view of a portion of yetanother exemplary embodiment showing less PCF and more conductivefilamentary structures than shown in FIG. 6 dispersed throughout theexemplary polymer base of FIG. 3 and with a multifunctional additivealso dispersed therein;

FIG. 8 is a representative cross-sectional view of a portion of anexemplary embodiment of a polymer base for a caulk;

FIG. 9 is a representative cross-sectional view of a portion of anotherexemplary embodiment showing PCF dispersed throughout the exemplarypolymer base of FIG. 8;

FIG. 10 is a representative cross-sectional view of a portion of stillanother exemplary embodiment showing PCF and conductive filamentarystructures dispersed throughout the exemplary polymer base of FIG. 8;and

FIG. 11 is a representative cross-sectional view of a portion of yetanother exemplary embodiment showing PCF and conductive filamentarystructures dispersed throughout the exemplary polymer base of FIG. 8 andwith multifunctional additives also dispersed therein.

REFERENCE NUMERALS system 10 precision-chopped fiber(s) or PCF 12 metalcoating or nickel coating 14 fiber(s) 16 polymer base 18 paint orelectrically conductive paint 20 conductive filamentary structure(s) 22electron transport pathway(s) 24 functional additive(s) 26 caulk 28second additive 32 first additive 30

DETAILED DESCRIPTION OF THE INVENTION

The exemplary embodiments of the present disclosure will be bestunderstood by reference to the drawings, wherein like parts aredesignated by like numerals throughout. It will be readily understoodthat the components of the exemplary embodiments of the presentinvention, as generally described and illustrated in the figures herein,could be arranged and designed in a wide variety of differentconfigurations. Thus, the following more detailed description of theexemplary embodiments, as represented in the Figures, is not intended tolimit the scope of the invention, as claimed, but is merelyrepresentative of exemplary embodiments of the disclosure.

Herein, the acronym “PCF” means precision-chopped fiber(s).Precision-chopped fiber includes fibers chopped to short, precisemillimeter and sub-millimeter lengths, and may be coated or non-coated.Typically, PCF may act as a conductive additive to paints, gaskets,sealants, molding compounds, adhesives, mortar-based materials, and thelike to enhance the conductivity of the product to which they are added.PCF is an off-the-shelf product available from Conductive CompositesCompany, but may also be obtained from any number of fiber converterssuch as Engineered Fiber Technology, LLC in Shelton, Conn.

The term “organic” refers to a class of chemical compounds that includesthose existing in or derived from plants or animals and also includescompounds of carbon.

This detailed description, with reference to the drawings, describes asystem 10 of components (FIGS. 4-7 and 9-11) used in exemplaryembodiments and the methodology for controlling what properties aremanifested in various paints and/or caulks so that other functionaladditives may be inserted.

Turning to FIG. 1, an exemplary embodiment of a single precision-choppedfiber 12 (“PCF”) has a metal coating 14 enclosing a fiber 16 is shown.FIG. 1 is a schematic depiction (not drawn to scale, but exaggeratingthe dimensions so that the basic structure may be better understood) ofa single PCF 12 with a portion of the metal coating 14 removed to revealthe fiber 16. Exemplary PCF 12 is precision chopped to lengths of 0.05millimeters to 3 millimeters so that when added to a paint or caulkpolymer, the paint may be applied by spraying, rolling, and/or brushingusing conventional techniques and the caulk, being pliable, may bedispensed from a tube. The fiber 16 of the PCF 12 may comprise any typeof fibrous substrate, such as, for example, carbon fiber, cellulosefiber, cotton fiber, natural fibers, Kevlar, rayon, synthetic fibers,and nanofibers. This list of fibrous substrates is not intended to beexhaustive. Those skilled in the art are aware and may become aware ofother fibrous substrates that may be used. Such additional substratesare contemplated to fall within the scope of this disclosure.

As one example, carbon fiber 16 may be used, and because carbon hasconductivity it offers some properties not available by usingnon-conductive fibers 16 as the substrate. Other types of fibers 16 haveother characteristics that may bring other desired results to a paint orcaulk. An exemplary fiber 16 may have a diameter of 3 to 7 microns.

FIG. 2 shows the metal coating 14 encircling the fiber 16. The fiber 16may be coated with a known conductive metal, including but not limitedto nickel, aluminum, copper, silver, and gold. This list of conductivemetals is not intended to be exhaustive. Those skilled in the art areaware and may become aware of other conductive metals or alloys thereofthat may be used. Such additional metals or alloys thereof arecontemplated to fall within the scope of this disclosure.

An example thickness of a nickel coating may be 5 to 500 nanometers, anddepending on the type, diameter, and length of the fiber 16 and the typeof metal coating, this range of thickness correlates the metal coating16 to about 15% to 78% of the PCF 12 by weight.

In one preferred embodiment, an exemplary nickel-coated carbon fiber PCF12 may have a carbon fiber 16 having a diameter of 4 to 7 microns and anickel coating of 50 to 500 nanometers, and preferably is precisionchopped to a length from 0.1 millimeters to 1 millimeter. Anickel-coated carbon fiber PCF 12 with a carbon fiber 16 having adiameter of 7 microns and a nickel coating of 80 nanometers, andprecision chopped to a length of 0.1 millimeters to 1 millimeter yieldsa PCF 12 that is 20% nickel by weight, and is particularly suitable forpaints with electrostatic discharge capability. PCF 12 that are 40%nickel by weight has been demonstrated to be particularly suitable forshielding. An exemplary system 10 will become more conductive by usingnickel-coated fibers 16 with higher coating thickness and/or higher PCF12 loading into the system 10 and/or increasing PCF 12 length to providea longer conductive path. However, fiber 16 length adversely affectsdispersion requiring a balance to be struck between ease of dispersionand length of fiber. Thus, a 40% nickel coating is preferable for higherconductivity applications such as shielding. Conductivity evolves fromthe onset of establishing an electrical percolation network.Consequently, the onset of an electrical percolation is particularlyimportant for low conductivity applications, such as electrostaticdissipation and electrostatic discharge. To that end, a unit weight offiber with less nickel coating will yield more length of fiber per unitweight. Thus, for the same fiber loading into the system 10 matrix, a20% nickel-coated fiber 16 will establish percolation at loadings lowerthan a 40% nickel-coated fiber 16, making 20% fiber particularlysuitable for electrostatic dissipation and electrostatic dischargeapplications. It has been determined that electrostatic discharge isbest established using 20% fiber at lengths precision chopped to 0.5millimeters or greater.

FIG. 3 is a representative cross-sectional end view of a portion of anexemplary embodiment of a polymer base 18 for an electrically conductivepaint 20. Paints are made with a wide range of viscosity, types ofpolymer bases, and other variables and characteristics. In eachexemplary embodiment of the system 10, the conductivity is determined asa function of the polymer type. For instance, and by way of example onlyand not to limit the invention to any particular polymer base or groupof polymer bases, a urethane base is more conductive than an acrylicbase which, in turn, is more conductive than an epoxy base. Therefore, adifferent blend of components may be used to achieve desired propertiesin an electrically conductive paint 20 having a urethane base versus anacrylic base or an epoxy base.

FIG. 4 is a representative cross-sectional view of a portion of anexemplary embodiment showing PCF 12 dispersed throughout the exemplarypolymer base 18 of FIG. 3. In the present state of the art, conductivepaints are heavily loaded with silver or carbon to introduceconductivity. Because conductive paints are so heavily loaded to achieveconductivity, viscosity is high and loading other additives is precludedor severely limited. Also, paints having electrostatic discharge orshielding capability that use the present state of the art, areexpensive, complex to make, thick, unable to receive other functionaladditive loading.

However, the system 10 of the present disclosure provides moreefficient, cost-effective, efficacious electrically conductive paints 20with a range of electromagnetic properties, flowable viscosity, and havemultifunctional capabilities while providing desired electromagneticproperties. Introducing a dispersal of PCF 12 into the polymer base 18,as shown in FIG. 4, yields an electrically conductive paint 20 havingdesired electromagnetic properties over a full electromagnetic range(10⁸ to 10⁻³ ohm-cms), including electrostatic dissipation,electrostatic discharge, and shielding with lower loadings of PCF 12that reduces viscosity and the additional unloaded portion of theelectrically conductive paint 20 may now receive other multifunctionalmaterials.

The PCF 12 is distinguishable from random-chopped fibers and milledfibers that are known and used in the art. By their very nature,random-chopped fibers and milled fibers have an excessively broaddistribution of fiber lengths. The use of random-chopped fibers andmilled fibers have significant drawbacks including high loading toachieve desired conductivity, high viscosity, and constrainedpercolation. By using PCF 12, better percolation and conductivity, andlower and more controllable viscosity and loading is achieved across thedesired range of electromagnetic properties (10⁸ to 10⁻³ ohm-cms).

Exemplary embodiments of the electrically conductive paints 20 of thepresent disclosure may comprise two or three basic components;namely, 1) precision-chopped fiber (PCF) 12; 2) optionally, a conductivefilamentary structure 22 having a high aspect ratio (See FIGS. 5-7); 3)a paint base polymer 18; and 4) optionally having a viscosity adjustingsolvent. By varying the amount and types of these three principalcomponents, desired electromagnetic properties may be achieved in lowcost, low loading, and low viscosity, efficacious paints 20 producedefficiently. For some exemplary embodiments, the use of PCF 12 alonedispersed within the polymer base 18 may achieve a desiredelectromagnetic property for a desired purpose or application.

FIG. 5 is a representative cross-sectional view of a portion of anotherexemplary embodiment showing conductive filamentary structures 22dispersed throughout the exemplary polymer base 18 of FIG. 3. Theconductive filamentary structure 22, such as a metal filamentarystructure 22, having a high aspect ratio, may be nickel nanostrands (seeU.S. Pat. Nos. 7,935,415 and 7,947,773) or a metal filamentary powder,such as but not limited to a nickel powder, provided each has an aspectratio greater than one, and in some embodiments the metal filamentarypowder preferably having branching. Nanostrands have branching and mayalso provide additional mechanical strength to the composite.

FIG. 6 is a representative cross-sectional view of a portion of stillanother exemplary embodiment showing PCF 12 and conductive filamentarystructures 22 dispersed throughout the exemplary polymer base 18 of FIG.3. The most basic parameters fall into the combination of two or threecategories; 1) the fiber properties of the PCF 12; including length,diameter and metal-coating 14 thickness; 2) the properties of theconductive filamentary structure 22 having a high aspect ratio,generally being approximately either sub-micron or larger than a micronin base diameter; and 3) the dielectric properties of the polymer base18.

The paint polymer base 18 may be water-borne or solvent-borne, one-partor two-part. The type of polymer base 18 may be selected for a desiredpurpose and will carry a load content of the PCF 12 and optionallyhigh-aspect ratio, conductive filamentary structure 22 fine-tuned sothat it achieves a desired electromagnetic property such aselectrostatic dissipation, electrostatic discharge, or shielding. ThePCF 12 and high-aspect ratio, conductive filamentary structure 22 worktogether to create a comprehensive network of electron transportpathways 24. It should be understood that the electron transportpathways 24 that are created do not require the PCF 12 and/or conductivefilamentary structures 22 to touch each other. They need only besufficiently proximate to each other to transport electrons (acting muchlike an antennae).

The physical nature of PCF 12 and the high-aspect ratio, conductivefilamentary structure(s) 22 facilitates the inter-fiber electrontransport within the paint 20 volume. The PCF 12 act much like logsbeing elongated linear electron transport conduits and the conductivefilamentary structures 22 act much like tumble weeds that electricallyinterconnect the logs. For some exemplary embodiments, the use of PCF 12alone dispersed within a polymer base 18 may achieve a desiredelectromagnetic property for a desired purpose or application. By addingconductive filamentary structures 22 into the polymer base 18, theloading of PCF 12 may be reduced commensurately, reducing cost,viscosity, and providing more space for multifunctional additives.

By matching the interplay of the fiber properties of the PCF 12 and theproperties of the conductive filamentary structure 22 (for example, anickel filamentary structure) with dielectric properties of the polymer18, the load ratio of PCF 12 and nickel filamentary structure 22 topolymer 18 to achieve electrostatic discharge may be determined andfine-tuned for that polymer 18. Generally, PCF 12 and nickel filamentarystructure 22 may be added to increase conductivity to achieve a fullrange of desired electromagnetic properties (10⁸ to 10⁻³ ohm-cms) andmore robust functionality capabilities.

The interrelation of the PCF 12-metal (nickel) content, fiber 16diameter, and fiber 16 length, when considered with the aspect ratio,base diameter, and the amount of branching exhibited by the conductive(nickel) filamentary structure 22, whether a filamentary powder ornanostrand, provides the desired conductivity. When additionallyconsidered with the dielectric and polar properties of the polymer 18,the combination of PCF 12, conductive filamentary structure 22, andpolymer 18 creates a highly complex electron transport system which isdifficult to model; however, the electron transport system may bestandardly optimized by those skilled in the art through empiricalderivation.

A known quantity of a certain PCF 12 (fiber diameter, length, metal(nickel) content) may demonstrate more conductivity through increasingthe addition of the conductive (nickel) filamentary structures 22.Consequently, the loading percentage of PCF 12 may be reducedsignificantly because of the increased conductive (nickel) filamentarystructures 22. Therefore, the balance of the quantity and type of PCF 12against the quantity and type of conductive (nickel) filamentarystructures 22 may be used to engineer the desired viscosity, electricalconductivity, and functionality.

By using PCF 12 and/or a nickel filamentary structures 22 having a highaspect ratio dispersed uniformly within a paint polymer base 18, desiredelectromagnetic properties (for example, a range including electrostaticdissipation and electrostatic discharge with volume resistivity rangingfrom 10⁸ to 10³ ohm-cm) may be achieved while maintaining lower loadsand therefore lower viscosity than known conductive paints.

FIG. 7 is a representative cross-sectional view of a portion of yetanother exemplary embodiment showing less PCF 12 and more conductivefilamentary structures 22 than shown in FIG. 6 dispersed throughout theexemplary polymer base of FIG. 3. The exemplary embodiment shown in FIG.7 depicts that by increasing conductive filamentary structures 22 lessPCF 12 may be needed to achieve a particular electromagnetic property.

Also, because the desired electromagnetic properties, such aselectrostatic dissipation, electrostatic discharge, and shielding, canbe achieved at lower loads and lower viscosity, the exemplary paints 20of the present disclosure may have robust functionality. Other particlesmay be loaded as functional additives 26 giving the paints 20 otherfunctions. By way of example only, and not to be construed as limiting,functional additives 26 such as coloring particles, hardening agentssuch as silicon carbide, lubricating agents, and magnetic particles haveroom in the matrix to be added to the extent that they do notfunctionally reduce the desired conductivity. Hence, colors of suchpaints 20 now may be achieved across a broader spectrum of colors andmay be more vibrant. The paints 20 may harden faster and exhibit greaterhardness. Further functionality may be exhibited by having differentfunctions in different layers (coats) of the paint 20. Also, otherdesirable functions now may be exhibited in the paints 20 withoutfunctionally sacrificing the needed conductivity.

FIG. 8 is a representative cross-sectional view of a portion of anexemplary embodiment of a polymer base 18 for an electrically conductivecaulk 28. Similar to paints 20, caulks 28 also are made with a widerange of viscosity, types of polymer bases 18, and other variables andcharacteristics. In each exemplary embodiment of the system 10, theconductivity is determined as a function of the polymer type 18. Forinstance, and by way of example only and not to limit the invention toany particular polymer base 18 or group of polymer bases 18, a urethanebase is more conductive than an acrylic base which, in turn, is moreconductive than an epoxy base. Therefore, a different blend ofcomponents may be used to achieve desired properties in a caulk 28having a urethane base versus an acrylic base or an epoxy base.

FIG. 9 is a representative cross-sectional view of a portion of anotherexemplary embodiment showing PCF 12 dispersed throughout the exemplarypolymer base 18 of FIG. 8. In the present state of the art, conductivecaulks 28, like conductive paints 20, are heavily loaded with silver orcarbon to introduce conductivity. Because conductive caulks are soheavily loaded to achieve conductivity, viscosity is high and loadingother additives 26 is precluded or severely limited. Also, caulks havingelectrostatic discharge or shielding capability that use the presentstate of the art, are expensive, complex to make, thick, unable toreceive other functional additive 26 loading.

However, the system 10 of the present disclosure provides moreefficient, cost-effective, efficacious electrically conductive caulk 28with a range of electromagnetic properties, pliable viscosity, and havemultifunctional capabilities while providing desired electromagneticproperties. Introducing a dispersal of PCF 12 into the polymer base 18yields an electrically conductive caulk 28 having desiredelectromagnetic properties over a full electromagnetic range (10⁸ to10⁻³ ohm-cms), including electrostatic dissipation, electrostaticdischarge, and shielding with lower loadings of PCF 12 that reducesviscosity and the additional unloaded portion of the electricallyconductive caulk 28 may now receive other multifunctional materials(functional additives 26).

The PCF 12 is distinguishable from random-chopped fibers and milledfibers that are known and used in the art. By their very nature,random-chopped fibers and milled fibers have an excessively broaddistribution of fiber lengths. The use of random-chopped fibers andmilled fibers have significant drawbacks including high loading toachieve desired conductivity, high viscosity, and constrainedpercolation. By using PCF 12, better percolation and conductivity, andlower and more controllable viscosity and loading is achieved across thedesired range of electromagnetic properties (10⁸ to 10⁻³ ohm-cms).

Exemplary embodiments of the electrically conductive caulks 28 of thepresent disclosure may comprise two or three basic components;namely, 1) precision-chopped fiber (PCF) 12; 2) optionally, a conductivefilamentary structure 22 having a high aspect ratio (See FIGS. 10-11);3) a caulk polymer base 18; and 4) optionally having a viscosityadjusting solvent. By varying the amount and types of these threeprincipal components, desired electromagnetic properties may be achievedin low cost, low loading, and low viscosity, efficacious caulks 28produced efficiently. For some exemplary embodiments, the use of PCF 12alone dispersed within the polymer base 18 of the caulk 28 may achieve adesired electromagnetic property for a desired purpose or application.

FIG. 10 is a representative cross-sectional view of a portion of stillanother exemplary embodiment showing PCF 12 and conductive filamentarystructures 22 dispersed throughout the exemplary polymer base 18 of FIG.8. The polymer base 18 for a caulk 28 may be water-borne orsolvent-borne, one-part or two-part. The type of caulk 28 selected for adesired purpose will carry a load content of the PCF 12 and optionallyhigh-aspect ratio, conductive filamentary structure 22 fine-tuned sothat it achieves a desired electromagnetic property such aselectrostatic dissipation, electrostatic discharge, or shielding. ThePCF 12 and high-aspect ratio, conductive filamentary structures 22 worktogether to create a comprehensive network of electron transportpathways 24. The physical nature of PCF 12 and the high-aspect ratio,conductive filamentary structure(s) 22 facilitates the inter-fiberelectron transport within the caulk 28 volume. The PCF 12 act much likelogs being elongated linear electron transport conduits and theconductive filamentary structures 22 act much like tumble weeds thatelectrically interconnect the logs. For some exemplary embodiments, theuse of PCF 12 alone dispersed within a polymer base 18 may achieve adesired electromagnetic property for caulk 28 having a desired purposeor application. By adding conductive filamentary structures 22 into thepolymer base 18, the loading of PCF 12 may be reduced commensurately,reducing cost, viscosity, and providing more space for multifunctionaladditives 26.

By matching the interplay of the fiber properties of the PCF 12 and theproperties of the conductive filamentary structure 22 (for example, anickel filamentary structure 22) with dielectric properties of thepolymer 18, the load ratio of PCF 12 and nickel filamentary structure 22to polymer 18 to achieve electrostatic discharge may be determined andfine-tuned for that polymer 18, whether it be a paint 20 or a caulk 28.Generally, PCF 12 and nickel filamentary structures 22 may be added toincrease conductivity to achieve a full range of desired electromagneticproperties (10⁸ to 10⁻³ ohm-cms) and more robust functionalitycapabilities.

The interrelation of the PCF 12-metal (nickel) content, fiber 16diameter, and fiber 16 length, when considered with the aspect ratio,base diameter, and the amount of branching exhibited by the conductive(nickel) filamentary structure 22, whether a filamentary powder ornanostrand, provides the desired conductivity. When additionallyconsidered with the dielectric and polar properties of the polymer 18,the combination of PCF 12, conductive filamentary structure 22, andpolymer 18 creates a highly complex electron transport system which isdifficult to model; however, the electron transport system may bestandardly optimized by those skilled in the art through empiricalderivation.

A known quantity of a certain PCF 12 (fiber diameter, length, metal(nickel) content) may demonstrate more conductivity through increasingthe addition of the conductive (nickel) filamentary structure 22component. Consequently, the loading percentage PCF 12 may be reducedsignificantly because of the increased conductive (nickel) filamentarystructure 22 component. Therefore, the balance of the quantity and typeof PCF 12 against the quantity and type of conductive (nickel)filamentary structure 22 may be used to engineer the desired viscosity,electrical conductivity, and functionality.

By using PCF 12 and/or nickel filamentary structures 22 having a highaspect ratio dispersed uniformly within a polymer base 18 for a paint 20or caulk 28, desired electromagnetic properties (for example, a rangeincluding electrostatic dissipation and electrostatic discharge withvolume resistivity ranging from 10⁸ to 10³ ohm-cm) may be achieved whilemaintaining lower loads and therefore lower viscosity than knownconductive paints and caulks.

FIG. 11 is a representative cross-sectional view of a portion of yetanother exemplary embodiment showing PCF 12 and conductive filamentarystructures 22 dispersed throughout the exemplary polymer base 18 of FIG.8 with multiple functional additives 26 (for example, a first additive30 and a second additive 32) also dispersed therein.

Also, because the desired electromagnetic properties, such aselectrostatic dissipation, electrostatic discharge, and shielding, canbe achieved at lower loads and lower viscosity, the exemplary caulks 28of the present disclosure may have robust functionality. Other particlesmay be loaded as functional additives 26 giving the caulks 28 otherfunctions. By way of example only, and not to be construed as limiting,functional additives 26 such as coloring particles, hardening agentssuch as silicon carbide, lubricating agents, and magnetic particles haveroom in the matrix to be added to the extent that they do notfunctionally reduce the desired conductivity. Hence, colors of suchcaulks 28 now may be achieved across a broader spectrum of colors andmay be more vibrant. The caulks 28 may harden faster and exhibit greaterhardness. Also, other desirable functions now may be exhibited in thecaulks 28 without functionally sacrificing the needed conductivity.

As depicted in FIG. 11 as an example of a first additive 30 and a secondadditive 32, multiple functional additives 26 may be added to thepolymer base 18 so long as there remains room within the polymer base 18and the first additive or second additive or any other additionaladditive does not sacrifice the needed conductivity.

Interrelated methods are used to achieve a desired conductivity thatwill cause the paint 20 or caulk 28 to manifest the desiredelectromagnetic properties. Those skilled in the art of electrontransport through materials, armed with this disclosure, intuitively andreadily can determine and fine tune the interrelationships of thecomponents to achieve the desired electromagnetic properties to beexhibited by the paint 20 and caulk 28 through known empirical means,and without undue experimentation.

For exemplary methods or processes of the invention, the sequence and/orarrangement of steps described herein are illustrative and notrestrictive. Accordingly, although steps of various processes or methodsmay be shown and described as being in a sequence or temporalarrangement, the steps of any such processes or methods are not limitedto being carried out in any specific sequence or arrangement, absent anindication otherwise. Indeed, the steps in such processes or methodsgenerally may be carried out in different sequences and arrangementswhile still falling within the scope of the present invention.

Additionally, any references to advantages, benefits, unexpectedresults, preferred materials, or operability of the present inventionare not intended as an affirmation that the invention has beenpreviously reduced to practice or that any testing has been performed.Likewise, unless stated otherwise, use of verbs in the past tense(present perfect or preterit) is not intended to indicate or imply thatthe invention has been previously reduced to practice or that anytesting has been performed.

Exemplary embodiments of the present invention are described above. Noelement, act, or instruction used in this description should beconstrued as important, necessary, critical, or essential to theinvention unless explicitly described as such. Although only a few ofthe exemplary embodiments have been described in detail herein, thoseskilled in the art will readily appreciate that many modifications arepossible in these exemplary embodiments without materially departingfrom the novel teachings and advantages of this invention. Accordingly,all such modifications are intended to be included within the scope ofthis invention as defined in the appended claims.

In the claims, any means-plus-function clauses are intended to cover thestructures described herein as performing the recited function and notonly structural equivalents, but also equivalent structures. Thus,although a nail and a screw may not be structural equivalents in that anail employs a cylindrical surface to secure wooden parts together,whereas a screw employs a helical surface, in the environment offastening wooden parts, a nail and a screw may be equivalent structures.Unless the exact language “means for” (performing a particular functionor step) is recited in the claims, a construction under Section 112 isnot intended. Additionally, it is not intended that the scope of patentprotection afforded the present invention be defined by reading into anyclaim a limitation found herein that does not explicitly appear in theclaim itself.

While specific embodiments and applications of the present inventionhave been described, it is to be understood that the invention is notlimited to the precise configuration and components disclosed herein.Various modifications, changes, and variations which will be apparent tothose skilled in the art may be made in the arrangement, operation, anddetails of the methods and systems of the present invention disclosedherein without departing from the spirit and scope of the invention.

Those skilled in the art will appreciate that the present embodimentsmay be embodied in other specific forms without departing from itsstructures, methods, or other essential characteristics as broadlydescribed herein and claimed hereinafter. The described embodiments areto be considered in all respects only as illustrative, and notrestrictive. The scope of the invention is, therefore, indicated by theappended claims, rather than by the foregoing description. All changesthat come within the meaning and range of equivalency of the claims areto be embraced within their scope.

What is claimed is:
 1. An electrically conductive paint that may beapplied by spraying, rolling, and/or brushing using conventionaltechniques, the electrically conductive paint comprising: a plurality ofmetal-coated fibers, the metal-coated fibers comprise a fibroussubstrate and a metal coating and the metal-coated fibers beingprecision chopped to lengths of 0.05 millimeters to 1 millimeter; aplurality of conductive filament structures having a branched structureand a high-aspect ratio; and a polymer base, the metal-coated fibers andthe 0% or more of conductive filament structures being disperseduniformly within the polymer base such that the volume resistivity ofthe electrically conductive paint ranges from 10⁸ to 10⁻³ ohm-cms. 2.The electrically conductive paint of claim 1 wherein the fibers of themetal-coated fibers are selected from the group of fibers consisting ofcarbon fiber, cellulose fiber, cotton fiber, natural fibers, Kevlar,rayon, synthetic fibers, and nanofibers.
 3. The electrically conductivepaint of claim 1 wherein the metal-coated fibers comprise carbon fiber.4. The electrically conductive paint of claim 2 wherein the carbon fiberhas a diameter ranging from 3 microns up to 7 microns.
 5. Theelectrically conductive paint of claim 1 wherein the metal coatingcomprises nickel.
 6. The electrically conductive paint of claim 5wherein the nickel metal coating has a thickness such that the nickelranges from 15% to 75% of the metal-coated fiber by weight.
 7. Theelectrically conductive paint of claim 5 wherein the nickel metalcoating has a thickness such that the nickel is about 20% of themetal-coated fiber by weight.
 8. The electrically conductive paint ofclaim 5 wherein the nickel metal coating has a thickness such that thenickel is about 40% of the metal-coated fiber by weight.
 9. Theelectrically conductive paint of claim 1 wherein the volume resistivityof the electrically conductive paint ranges from 10⁸ to 10³ ohm-cms. 10.The electrically conductive paint of claim 1 further comprising afunctional additive.
 11. The electrically conductive paint of claim 10wherein the functional additive is selected from the group of functionaladditives consisting of coloring particles, hardening agents,lubricating agents, magnetic particles, and any combination of suchadditives.
 12. A multifunctional, electrically conductive paint that maybe applied by spraying, rolling, and/or brushing using conventionaltechniques, the electrically conductive paint comprising: a plurality ofmetal-coated fibers, the metal-coated fibers comprise a fibroussubstrate and a metal coating and the metal-coated fibers being choppedto lengths of 0.05 millimeters to 1 millimeter; a plurality ofconductive filament structures having a branched structure and ahigh-aspect ratio; a functional additive, and a polymer base, themetal-coated fibers and the 0% or more of conductive filament structuresbeing dispersed uniformly within the polymer base such that the volumeresistivity of the electrostatic discharge paint ranges from 10⁸ to 10⁻³ohm-cms.
 13. The multifunctional, electrically conductive paint of claim12 wherein the metal coating comprises nickel.
 14. The multifunctional,electrically conductive paint of claim 13 wherein the nickel metalcoating has a thickness such that the nickel ranges from 15% to 75% ofthe metal-coated fiber by weight.
 15. The multifunctional, electricallyconductive paint of claim 13 wherein the nickel metal coating has athickness such that the nickel is about 20% of the metal-coated fiber byweight.
 16. The multifunctional, electrically conductive paint of claim13 wherein the nickel metal coating has a thickness such that the nickelis about 40% of the metal-coated fiber by weight.
 17. An electricallyconductive caulk that is pliable and dispensable from a tube, theelectrostatic discharge caulk comprising: a plurality of metal-coatedfibers, the metal-coated fibers comprise a fibrous substrate and a metalcoating and the metal-coated fibers being chopped to lengths of 0.1millimeters to 1 millimeter; a plurality of conductive filamentstructures having a branching structure and a high-aspect ratio; and apolymer base, the metal-coated fibers and conductive structures beingdispersed uniformly within the polymer base such that the volumeresistivity of the electrically conductive caulk ranges from 10⁸ to 10⁻³ohm-cms.
 18. The electrically conductive caulk of claim 17 wherein themetal-coated fibers comprise carbon fiber.
 19. The electricallyconductive caulk of claim 17 wherein the metal coating comprises nickel.20. The electrically conductive caulk of claim 17 further comprising afunctional additive.